Aminoacyl t-RNA is not required for

The enzymes aminoacyl tRNA synthetases activate the amino acids. The enzyme is highly selective in the recognition of both the amino acid and the transfer RNA acceptor. There is at least one tRNA for each of the 20 amino acids. Eg: hydroxylysine is the active form of lysine .hence not recognised by tRNA The D arm of tRNA is very impoant for the recognition by the enzyme. The CCA 3&; terminus of the acceptor&;s arm carries amino acid (Figs 41.14A and B). iii. Amino acid is first activated with the help of ATP. Then the carboxyl group of the amino acid is esterified with 3&; hydroxyl group of tRNA. Aminoacyl tRNA synthetase Amino acid ----------------> Aminoacyl tRNA + tRNA + ATP + AMPRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 490